Furthermore it was also shown that whichever "theory" you believe about willpower (consumable resource vs habituation like a trainable muscle) will impact your performance. If you believe it's not a finite resource but something that gets more plentiful and strong the more you use it, you will appear to confirm this theory.

Source: this is the specialty of Veronika Job, see her work here: https://tu-dresden.de/mn/psychologie/iaosp/sozial/die-profes...